Investigators are examining whether four recent deaths in three Eastern cities might be linked to a bad batch of the club drug “Molly,” a supposedly pure form of ecstasy, or MDMA.

Three of the deaths occurred on August 31. Two people died at the Electric Zoo music festival on New York’s Randall’s Island, forcing city officials to cancel the final day of proceedings. That same day, in Washington, D.C., 19-year-old University of Virginia student Mary Goldsmith collapsed at a rave concert at a local nightclub called Echo Stage. She was rushed to a local hospital, where she was pronounced dead after attempts to revive her failed.

Three days earlier, another 19-year-old, Brittany Flannigan, a student at Plymouth State University in New Hampshire, took a fatal overdose while attending a concert at the House of Blues in Boston.

In addition to the deaths, four more people had to be hospitalized after overdosing on the drug at the Electric Zoo festival. In Boston, two other people suffered non-fatal overdoses of the drug at the same concert Flannigan was attending. Three days later, on the same Saturday as the deaths in New York and Washington, three people were treated for overdoses at another Boston-area concert venue, the Bank of America Pavilion. The Washington Post reported that authorities were investigating a nightclub in the Boston suburb of Quincy where 12 people suffered reported overdoses during the summer.

“There’s no ‘good batch’ of molly, MDMA, Ecstasy,” Anthony Pettigrew, a spokesman for the Drug Enforcement Agency’s New England division, told the Boston Herald “This is stuff that’s made in somebody’s bathtub in either Asia, the Netherlands, Canada, you have no idea what is in this stuff. Dealers want to make more money, so they’ll mix and adulterate the stuff with meth and any number of other drugs to addict people to it.”